Replacement metal gate process for vertical transport field-effect transistor with self-aligned shared contacts

ABSTRACT

A semiconductor structure includes a substrate, a bottom source/drain region disposed on a top surface of the substrate, and a plurality of fins disposed over a top surface of the bottom source/drain region. The fins provide vertical transport channels for one or more vertical transport field-effect transistors. The semiconductor structure also includes at least one self-aligned shared contact disposed between an adjacent pair of the plurality of fins. The adjacent pair of the plurality of fins includes a first fin providing a first vertical transport channel for a first vertical transport field-effect transistor and a second fin providing a second vertical transport channel for a second vertical transport field-effect transistor.

BACKGROUND

The present application relates to semiconductors, and morespecifically, to techniques for forming semiconductor structures.Semiconductors and integrated circuit chips have become ubiquitouswithin many products, particularly as they continue to decrease in costand size. There is a continued desire to reduce the size of structuralfeatures and/or to provide a greater amount of structural features for agiven chip size. Miniaturization, in general, allows for increasedperformance at lower power levels and lower cost. Present technology isat or approaching atomic level scaling of certain micro-devices such aslogic gates, field-effect transistors (FETs), and capacitors.

SUMMARY

Embodiments of the invention provide techniques for replacement metalgate processes for forming vertical transport field-effect transistorshaving self-aligned shared contacts.

In one embodiment, a semiconductor structure comprises a substrate, abottom source/drain region disposed on a top surface of the substrate, aplurality of fins disposed over a top surface of the bottom source/drainregion, the fins providing vertical transport channels for one or morevertical transport field-effect transistors, and at least oneself-aligned shared contact disposed between an adjacent pair of theplurality of fins, the adjacent pair of the plurality of fins comprisinga first fin providing a first vertical transport channel for a firstvertical transport field-effect transistor and a second fin providing asecond vertical transport channel for a second vertical transportfield-effect transistor.

In another embodiment, an integrated circuit comprises one or morevertical transport field-effect transistors comprising a substrate, abottom source/drain region disposed on a top surface of the substrate, aplurality of fins disposed over a top surface of the bottom source/drainregion, the fins providing vertical transport channels for the one ormore vertical transport field-effect transistors, and at least oneself-aligned shared contact disposed between an adjacent pair of theplurality of fins, the adjacent pair of the plurality of fins comprisinga first fin providing a first vertical transport channel for a firstVTFET and a second fin providing a second vertical transport channel fora second VTFET.

In another embodiment, a method of forming a semiconductor structurecomprises forming a bottom source/drain region over a top surface of asubstrate, forming a plurality of fins over a top surface of the bottomsource/drain region, the fins providing vertical transport channels forone or more vertical transport field-effect transistors, and forming atleast one self-aligned shared contact between an adjacent pair of theplurality of fins, the adjacent pair of the plurality of fins comprisinga first fin providing a first vertical transport channel for a firstvertical transport field-effect transistor and a second fin providing asecond vertical transport channel for a second vertical transportfield-effect transistor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a top-down view of a set of n-type field-effecttransistor (nFET) and p-type field-effect transistor (pFET) activeregions along with block masks for forming a dummy gate betweennFET-nFET and pFET-pFET regions, according to an embodiment of theinvention.

FIG. 2 depicts a top-down view of the FIG. 1 structure following a gateopen for nFET dummy gate pull for nFET work function metal definition,according to an embodiment of the invention.

FIG. 3 depicts a top-down view of the FIG. 2 structure following a gateopen for pFET dummy gate pull for pFET work function metal definition,according to an embodiment of the invention.

FIG. 4 depicts a top-down view of the FIG. 3 structure following a gateisolation cut between nFET-nFET or pFET-pFET by following an insulatorfilling, according to an embodiment of the invention.

FIG. 5 depicts a top-down view of the FIG. 4 structure following a gateopen to form a shared gate contact and following formation ofself-aligned bottom source/drain contacts, according to an embodiment ofthe invention.

FIG. 6 depicts a cross-sectional view of a structure including asubstrate, bottom source/drain regions, bottom spacer, fins, oxide, hardmask, interlayer and dielectric layer, according to an embodiment of theinvention.

FIG. 7 depicts a cross-sectional view of the FIG. 6 structure followingformation of a capping layer and formation of a dummy gate afterplanarization, according to an embodiment of the invention.

FIG. 8 depicts a cross-sectional view of the FIG. 7 structure followingrecess of the dummy gate, capping layer and dielectric layer, formationof a self-aligned spacer and formation of masks in the nFET-nFET andpFET-pFET shared regions as shown in FIG. 1, according to an embodimentof the invention.

FIG. 9 depicts a cross-sectional view of the FIG. 8 structure followinga self-aligned cut of the dummy gate, oxide fill and planarization ofthe oxide to stop on the hard mask, according to an embodiment of theinvention.

FIG. 10 depicts a cross-sectional view of the FIG. 9 structure followingformation of a mask to open top junctions for the nFET regions,according to an embodiment of the invention.

FIG. 11 depicts a cross-sectional view of the FIG. 10 structurefollowing formation of nFET top source/drain regions, according to anembodiment of the invention.

FIG. 12 depicts a cross-sectional view of the FIG. 11 structurefollowing formation of an encapsulation layer and mask to open topjunctions for the PFET regions, according to an embodiment of theinvention.

FIG. 13 depicts a cross-sectional view of the FIG. 12 structurefollowing formation of pFET top source/drain regions, according to anembodiment of the invention.

FIG. 14 depicts a cross-sectional view of the FIG. 13 structurefollowing removal of the encapsulation layer, recessing the nFET andpFET top source/drain regions, and formation of nitride layer on the topjunctions, according to an embodiment of the invention.

FIG. 15 depicts a cross-sectional view of the FIG. 14 structurefollowing formation of a mask to open the nFET-nFET shared region andfollowing removal of the dummy gate in the nFET-nFET shared region,according to an embodiment of the invention.

FIG. 16 depicts a cross-sectional view of the FIG. 15 structurefollowing formation of an nFET gate conductor, according to anembodiment of the invention.

FIG. 17 depicts a cross-sectional view of the FIG. 16 structurefollowing planarization of the nFET gate conductor, according to anembodiment of the invention.

FIG. 18 depicts a cross-sectional view of the FIG. 17 structurefollowing removal of the dummy gate in the pFET-pFET shared region,formation of the pFET gate conductor and planarization of the pFET gateconductor, according to an embodiment of the invention.

FIG. 19 depicts a cross-sectional view of the FIG. 18 structurefollowing formation of a mask to open the nFET-nFET and pFET-pFET sharedregions and following nFET-nFET and pFET-pFET isolation gate cut,according to an embodiment of the invention.

FIG. 20 depicts a cross-sectional view of the FIG. 19 structurefollowing formation of a self-aligned inner spacer, according to anembodiment of the invention.

FIG. 21 depicts a cross-sectional view of the FIG. 20 structurefollowing an oxide fill, according to an embodiment of the invention.

FIG. 22 depicts a cross-sectional view of the FIG. 21 structurefollowing formation of a mask to open the nFET-pFET shared gate region,according to an embodiment of the invention.

FIG. 23 depicts a cross-sectional view of the FIG. 22 structurefollowing formation of contact openings, according to an embodiment ofthe invention.

FIG. 24 depicts a cross-sectional view of the FIG. 23 structurefollowing formation of contact material, according to an embodiment ofthe invention.

FIG. 25 depicts a cross-sectional view of the FIG. 24 structurefollowing planarization to form contacts, according to an embodiment ofthe invention.

DETAILED DESCRIPTION

Illustrative embodiments of the invention may be described herein in thecontext of illustrative methods for replacement metal gate processes forforming vertical transport field-effect transistors, along withillustrative apparatus, systems and devices formed using such methods.However, it is to be understood that embodiments of the invention arenot limited to the illustrative methods, apparatus, systems and devicesbut instead are more broadly applicable to other suitable methods,apparatus, systems and devices.

A field-effect transistor (FET) is a transistor having a source, a gate,and a drain, and having action that depends on the flow of carriers(electrons or holes) along a channel that runs between the source anddrain. Current through the channel between the source and drain may becontrolled by a transverse electric field under the gate.

FETs are widely used for switching, amplification, filtering, and othertasks. FETs include metal-oxide-semiconductor (MOS) FETs (MOSFETs).Complementary MOS (CMOS) devices are widely used, where both n-type andp-type transistors (nFET and pFET) are used to fabricate logic and othercircuitry. Source and drain regions of a FET are typically formed byadding dopants to target regions of a semiconductor body on either sideof a channel, with the gate being formed above the channel. The gateincludes a gate dielectric over the channel and a gate conductor overthe gate dielectric. The gate dielectric is an insulator material thatprevents large leakage current from flowing into the channel whenvoltage is applied to the gate conductor while allowing applied gatevoltage to produce a transverse electric field in the channel.

Increasing demand for high density and performance in integrated circuitdevices requires development of new structural and design features,including shrinking gate lengths and other reductions in size or scalingof devices. Continued scaling, however, is reaching limits ofconventional fabrication techniques.

Vertical transport FETs (VTFETs) are being pursued as viable CMOSarchitectures for scaling to 7 nanometers (nm) and beyond. VTFETsprovide the opportunity for further device scaling compared with otherdevice architectures. However, several key device metrics are difficultto meet when forming VTFETs. Illustrative embodiments described hereinprovide an integration scheme to have replacement metal gate (RMG) withself-aligned gate cut and self-aligned bottom source/drain contacts.Advantageously, the self-aligned bottom source/drain contacts may beself-aligned to the gate cut for further device scaling.

Illustrative embodiments enable lateral dummy gate removal and gateconductor (e.g., work function metal (WFM)) fill for VTFETs. Someembodiments isolate all gates, which are self-aligned, and then pull outthe nFET and pFET dummy gates separately using self-aligned cuts. Sharedgates are then formed between nFET and pFET regions.

In some embodiments, the RMG process includes: forming a bottom junctionor bottom source/drain region; forming an interlayer (IL) and dielectric(e.g., high-K or HK dielectric); forming a dummy gate; forming a topspacer; performing a self-aligned cut of the dummy gate; forming a topjunction or top source/drain regions; performing a self-aligned cut ofan interlevel dielectric (ILD) to pull the dummy gate laterally for nFETand pFET regions individually; performing a self-aligned cut to isolatethe nFETs and pFETs individually by removing metals between thenFET-nFET (also referred to as n-n) and pFET-pFET (also referred to asp-p) regions; and opening the shared gate (also referred to as n-p)region and filling a metal to form an n-p shared gate CMOS structure.Such RMG processes are used to form RMG VTFETs, with a RMG gate withetched edge in like (e.g., n-n or p-p) regions, a bottom source/draincontact in like (e.g., n-n or p-p) regions between the etched RMG gateedges, bottom source/drain contacts in like (e.g., n-n or p-p) regionsthat are self-aligned to the cut RMG gate edges, and a RMG gate that isstripped in shared (e.g., n-p) regions. The nFET gate is electricallyconnected to the pFET gate with a strapping conductor that also connectsto back-end-of-line (BEOL) wiring.

Illustrative processes for forming VTFETs using RMG processes withself-aligned gate cut and self-aligned bottom source/drain contacts willnow be described with respect to FIGS. 1-25.

FIGS. 1-5 illustrate portions of the RMG process flow with top-downviews, while FIGS. 6-25 illustrates portions of the RMG process flowwith cross-sectional views. FIG. 1 shows a top down view 100 of sets ofactive regions 101-1 and 101-2 for nFET and pFET VTFETs, respectively.Also shown in the top-down view 100 is a block mask 103 for sharedregions (e.g., nFET-nFET or n-n shared regions for the active regions101-1 and pFET-pFET or p-p shared regions for the active regions 101-2).Also shown in FIG. 1 and subsequent top-down view in FIGS. 2-5 is a lineA-A, illustrating where the cross-sectional views of FIGS. 6-25 aretaken.

FIG. 2 depicts a top-down view 200 of the FIG. 1 structure following agate open process in an open mask 105-1 inside the block mask 103between the nFET active regions 101-1 for a dummy gate pull. FIG. 3depicts a top-down view 300 of the FIG. 2 structure following a gateopen process in the open mask 105-2 inside the block mask 103 betweenthe pFET active regions 101-2 for the dummy gate pull. It should beappreciated that the ordering of the dummy gate pull is not limited tonFET followed by pFET. In other embodiments, the dummy gate pull may beperformed for the pFET regions first followed by the nFET regions.

FIG. 4 shows a top-down view 400 of the FIG. 2 structure following gateisolation 107, such as using reactive ion etching (RIE) or anothersuitable planarization process, followed by insulator filling andplanarization.

FIG. 5 shows a top-down view 500 of the FIG. 4 structure following agate open in shared gate region (e.g., the nFET-pFET or n-p region) toform contacts 154-4 to the shared gate regions for respective “rows” ofthe nFET and pFET devices. It should be noted that although FIGS. 1-5illustrate an arrangement with four “rows” of the nFET and pFET devices,embodiments are not so limited. More or fewer than four rows of nFET andpFET devices may be formed as desired.

The top-down view 500 further illustrates self-aligned bottomsource/drain contacts 154-2 and 154-6 for the nFET active regions 101-1and pFET active regions 101-2, respectively, and gate contacts 154-8 and154-9 for nFET and pFET devices at the edges of each of the four rows.It should be noted that although FIGS. 1-5 illustrate two nFET and twopFET devices in each of the four rows, embodiments are not so limited.In other embodiments, more or fewer then two nFET and two pFET devicesmay be formed in each row, and there further may be different numbers ofnFET and pFET devices in each row.

Additional details regarding the RMG process for forming VTFETs will nowbe described with respect to the cross-sectional views of FIGS. 6-25.The cross-sectional views of FIGS. 6-25, as indicated above, are takenalong the line A-A in the top-down views of FIGS. 1-5 (e.g., along oneof the “rows” where nFET and pFET VTFETs are formed).

FIG. 6 shows a cross-sectional view 600 of a structure including asubstrate 102, a bottom junction or bottom source/drain region 104, abottom spacer 106, shallow trench isolations (STI) regions 108, fins110, oxide layer 112, interfacial layer 113, hard masks 114, anddielectric layer 116.

The substrate 102 may comprise a semiconductor substrate formed ofsilicon (Si), although other suitable materials may be used. Forexample, the substrate 102 can include any suitable substrate structure,e.g., a bulk semiconductor. The substrate 102 can include asilicon-containing material. Illustrative examples of Si-containingmaterials suitable for the substrate 102 can include, but are notlimited to, Si, silicon germanium (SiGe), silicon germanium carbide(SiGeC), silicon carbide (SiC) and multi-layers thereof. Althoughsilicon is the predominantly used semiconductor material in waferfabrication, alternative semiconductor materials can be employed asadditional layers, such as, but not limited to, germanium (Ge), galliumarsenide (GaAs), gallium nitride (GaN), SiGe, cadmium telluride (CdTe),zinc selenide (ZnSe), etc.

The size of the substrate 102 may vary, such as based on the number ofVTFETs that are to be formed thereon. The vertical thickness or heightof the substrate (in direction Y-Y′) may be in the range of 10micrometers (μm) to 100 millimeters (mm), although other heights aboveor below this range may be used as desired for a particular application.

The bottom junction or bottom source/drain region 104 may be suitablydoped, such as using ion implantation, gas phase doping, plasma doping,plasma immersion ion implantation, cluster doping, infusion doping,liquid phase doping, solid phase doping, etc. N-type dopants may beselected from a group of phosphorus (P), arsenic (As) and antimony (Sb),and p-type dopants may be selected from a group of boron (B), boronfluoride (BF₂), gallium (Ga), indium (In), and thallium (Tl). The bottomsource/drain regions 106 may be formed by an epitaxial growth process.In some embodiments, the epitaxy process comprises in-situ doping(dopants are incorporated in epitaxy material during epitaxy). Epitaxialmaterials may be grown from gaseous or liquid precursors. Epitaxialmaterials may be grown using vapor-phase epitaxy (VPE), molecular-beamepitaxy (MBE), liquid-phase epitaxy (LPE), rapid thermal chemical vapordeposition (RTCVD), metal organic chemical vapor deposition (MOCVD),ultra-high vacuum chemical vapor deposition (UHVCVD), low-pressurechemical vapor deposition (LPCVD), limited reaction processing CVD(LRPCVD), or other suitable processes. Epitaxial silicon, silicongermanium (SiGe), germanium (Ge), and/or carbon doped silicon (Si:C)silicon can be doped during deposition (in-situ doped) by addingdopants, such as n-type dopants (e.g., phosphorus or arsenic) or p-typedopants (e.g., boron or gallium), depending on the type of transistor.The dopant concentration in the source/drain can range from 1×10¹⁹ cm⁻³to 3×10²¹ cm⁻³, or preferably between 2×10²⁰ cm⁻³ to 3×10²¹ cm⁻³.

The bottom source/drain regions 104 may have a height or verticalthickness (in direction Y-Y′) in the range of 10 nanometers (nm) to 100nm, although other heights above or below this range may be used asdesired for a particular application.

The bottom spacer 106 is formed over the bottom source/drain regions104, such as using non-conformal deposition and etch-back processing(e.g., physical vapor deposition (PVD), high density plasma (HDP)deposition, etc.). The bottom spacer 106 may be formed of SiO₂, SiN,silicon carbide oxide (SiCO), silicon boron carbide nitride (SiBCN),etc., although other suitable materials may be used. The bottom spacers106 may have a height or vertical thickness (in direction Y-Y′) in therange of 3 nm to 15 nm, although other heights above or below this rangemay be used as desired for a particular application.

The STI regions 108 may be formed of a dielectric material such assilicon dioxide (SiO₂), silicon oxycarbide (SiOC), silicon oxynitride(SiON), etc. The STI regions 108 isolate the bottom junction or bottomsource/drain region 104 to provide separate addressability of thedifferent VTFETs that are formed.

The fins 110 provide the vertical transport channels for the resultingVTFETs. The fins 110 may be formed of the same material as the substrate102, and may be formed using sidewall image transfer (SIT) or othersuitable techniques such as lithography and etching includingreactive-ion etching (RIE), etc.

Each of the fins 110 may have a width or horizontal thickness (indirection X-X′) in the range of 5 nm to 15 nm, although other widthsabove or below this range may be used as desired for a particularapplication. Each of the fins 110 may have a height or verticalthickness (in direction Y-Y′) ranging from 15 nm to 100 nm, althoughother heights above or below this range may be used as desired for aparticular application. A spacing between adjacent ones of the fins 110may be in the range of 20 nm to 60 nm, although other spacing may beused as desired for a particular application.

An oxide layer 112 is formed over each of the fins 110. The oxide layer112 may be formed of silicon oxide (SiO_(x)) or another suitablematerial such as silicon oxynitride (SiO_(x)N_(y)), silicon oxycarbide(SiOC), etc. The oxide layer 112 may have a height or vertical thickness(in direction Y-Y′) ranging from 1 nm to 5 nm, although other heightsabove or below this range may be used as desired for a particularapplication.

The interfacial layer 113 is formed on sidewalls of the fins 110. Theinterfacial layer 113 may be formed of SiO₂ or another suitable materialsuch as SiO_(x)N_(y). The interfacial layer 113 may have a width orhorizontal thickness (in direction X-X′) ranging from 0.5 nm to 1.5 nm,although other widths above or below this range may be used as desiredfor a particular application. For clarity of illustration, theinterfacial layer 113 is not shown in subsequent FIGS. 7-25, although itis assumed that the interfacial layer 113 is present in the structuresshown in FIGS. 7-25.

Hard masks 114, also referred to herein as HM 114, are formed over theoxide 112 on top of each of the fins 110. The HM 114 may be formed of anitride such as silicon nitride (SiN) or another suitable material. TheHM 114 may have a height or vertical thickness (in direction Y-Y′) inthe range of 20 nm to 80 nm, although other heights above or below thisrange may be used as desired for a particular application. The HM 114may be patterned over an initial substrate, with the resulting substrate102 being formed by etching in the regions exposed by the HM 114 to formthe fins 110 from the initial substrate. In some embodiments, the HM 114may be formed as a multilayer, such as two layers of materials includinga nitride and oxide (e.g., SiN/SiO₂), or three layers of nitride andoxide materials such as (e.g., SiN/SiO₂/SiN, SiO₂/SiN/SiO₂), etc.

The dielectric layer 116 is formed over the entire structure asillustrated in FIG. 6. The dielectric layer 116 provides the gatedielectric for the resulting VTFETs. The dielectric layer 116 may beformed of a high-k dielectric material. Examples of high-k materialsinclude but are not limited to metal oxides such as hafnium oxide(HfO₂), hafnium silicon oxide (Hf—Si—O), hafnium silicon oxynitride(HfSiON), lanthanum oxide (La₂O₃), lanthanum aluminum oxide (LaAlO₃),zirconium oxide (ZrO₂), zirconium silicon oxide, zirconium siliconoxynitride, tantalum oxide (Ta₂O₅), titanium oxide (TiO₂), bariumstrontium titanium oxide, barium titanium oxide, strontium titaniumoxide, yttrium oxide (Y₂O₃), aluminum oxide (Al₂O₃), lead scandiumtantalum oxide, and lead zinc niobate. The high-k material may furtherinclude dopants such as lanthanum (La), aluminum (Al), and magnesium(Mg). The dielectric layer 116 may have a uniform thickness in the rangeof 1 nm to 3 nm, although other thicknesses above or below this rangemay be used as desired for a particular application.

FIG. 7 shows a cross-sectional view 700 of the FIG. 6 structurefollowing formation of a capping layer 118 and formation of a dummy gate120. The capping layer 118 may be deposited over the dielectric layer116. The capping layer 118 may be formed of titanium nitride (TiN) oranother suitable material such as tantalum nitride (TiN), titaniumsilicon nitride (TiSiN), etc. The capping layer 118 may have a uniformthickness in the range of 1 nm to 5 nm, although other thicknesses aboveor below this range may be used as desired for a particular application.

The dummy gate 120 may initially be deposited to fill the structure, andthen planarized using CMP or another suitable process such that a topsurface of the dummy gate 120 is substantially coplanar with that of thecapping layer 118. The dummy gate 120 may be formed of amorphous silicon(a-Si), amorphous silicon germanium (a-SiGe), SiO₂, titanium nitride(TiN) or another suitable material.

FIG. 8 shows a cross-sectional view 800 of the FIG. 7 structurefollowing recess of the dummy gate 120, capping layer 118 and dielectriclayer 116, formation of self-aligned spacers 122 and following formationof masks 124 in the n-n and p-p shared regions.

The dummy gate 120 may be recessed using a chemical or reactive-ionetching (ME) processes. The capping layer 118 and dielectric layer 116may be recessed using RIE or another suitable process. Following recess,the vertical thickness or height of the dummy gate 120, capping layer118 and dielectric layer 116 is below a top surface of the fins 110. Forexample, the height of the dielectric layer 116 on sidewalls of the fins110, measured from a top surface of the bottom spacer 106, may be in therange of 10 nm to 60 nm, although other heights above or below thisrange may be used as desired for a particular application so long as thedielectric layer 116, capping layer 118 and dummy gate 120 are recessedbelow a top surface of the fins 110.

Self-aligned spacers 122 are formed on exposed sidewalls of the fins110, oxide 112 and HM 114 as illustrated in FIG. 8. Formation of theself-aligned spacers may be achieved through a conformal depositionfollowed by RIE. The self-aligned spacers 122 may be formed of a nitridesuch as SiBCN, SiOC, SiCN, etc. At their widest points (e.g., proximatethe top surface of the recessed dummy gate 120), the self-alignedspacers 122 have a width or horizontal thickness (in direction X-X′)ranging from 10 nm to 20 nm. The width then tapers proximate the topsurface of the HM 114 to a width or horizontal thickness (in directionX-X′) ranging from 1 nm to 6 nm. The width of the self-aligned spacers122 at their widest and narrowest points may vary above or below theseranges as desired for a particular application, although there should besufficient spacing between the self-aligned spacers 122 for theself-aligned cuts in the n-p, n-n and p-p shared regions described infurther detail below.

The masks 124 cover the n-n and p-p shared regions as illustrated inFIG. 8. The materials used for the mask 124 may be a soft mask, such asan organic planarization layer (OPL), or a hard mask, such as TiN, SiO,etc. The widths of the masks 124 are such that each mask should fullycover the bottom space of the adjacent spacer 122.

FIG. 9 shows a cross-sectional view 900 of the FIG. 8 structurefollowing a self-aligned cut of the dummy gate 120 in the n-p sharedregion, and following fill and planarization of an oxide layer 126.

The self-aligned cut of the dummy gate 120 in the n-p shared regionremoves portions of the dummy gate 120 not covered by the self-alignedspacers 122, HM 114 or masks 124. Thus, as illustrated, the dummy gate120 in the n-p shared region is removed below the adjacent self-alignedspacers 122. In addition, the dummy gate 120 is removed in regions atthe edge of the structure outside the self-aligned spacers 122.

An oxide is then filled over the structure, and planarized using CMP orother suitable processing to form oxide layer 126. In some embodiments,and additional encapsulation layer (not shown in FIG. 9) is formed overthe structure prior to formation of the oxide layer 126. The oxide layer126 is planarized such that is top surface is substantially coplanarwith the top surface of the HM 114.

FIG. 10 shows a cross-sectional view 1000 of the FIG. 9 structurefollowing patterning of a mask 128 over the structure and followingopening of the nFET top junction (e.g., exposing top surfaces of thefins 110 in the nFET active regions 101-1) for subsequent epitaxialgrowth of top source/drain regions for the nFET VTFETs. The mask 128 maybe formed of SiN or another suitable material, and may be patternedusing RIE or other suitable processing. As illustrated, the openings inthe mask 128 are wider (e.g., in the range of 5 nm to 10 nm than that ofthe top surface of the fins 110 in the nFET active regions 101-1 suchthat portions of the self-aligned spacers 122 adjacent the fins 110 inthe nFET active regions 101-1 are removed during the top junction open.This, however, is not a requirement, and the mask 128 may be patternedsuch that only the HM 114 over the top surface of the fins 110 isremoved and not portions of the self-aligned spacers 122 so long as goodepitaxial growth may be achieved after such patterning. The HM 114 andportions of the self-aligned spacers adjacent the fins 110 in the nFETactive regions 101-1 are removed using RIE and wet etch or othersuitable processing.

FIG. 11 shows a cross-sectional view 1100 of the FIG. 10 structurefollowing formation of top junctions or top source/drain regions 130 forthe nFET VTFETs. The top source/drain regions 130 may be formed usingprocessing similar to that described above with respect to formation ofthe bottom source/drain region 104. The top source/drain regions 130utilize n-type dopants. The mask 128 is removed using, RIE, wet etch,and/or CMP or other suitable processing.

FIG. 12 shows a cross-sectional view 1200 of the FIG. 11 structurefollowing formation of an encapsulation layer 132 to protect the nFETtop source/drain regions 130 during formation of the pFET topsource/drain regions. The encapsulation layer 132 may be formed of anitride such as SiN or another suitable encapsulating material.

A mask 134 is then patterned over the structure to open the pFET topjunction (e.g., exposing top surfaces of the fins 110 in the pFET activeregions 101-2) for subsequent epitaxial growth of the top source/drainregions for the pFET VTFETs. The mask 134 may be formed of similarmaterials and with similar processing as that described above withrespect to mask 128. Also similar to mask 128, the openings in the mask132 are wider (e.g., in the range of 5 nm to 10 nm) than that of the topsurface of the fins 110 in the pFET active regions 101-2 such thatportions of the self-aligned spacers 122 adjacent the fins 110 in thepFET active regions 101-2 are removed during the top junction open.Again, it should be noted that this is not a requirement and that themask 134 may be patterned such that only the HM 114 is removed and notportions of the self-aligned spacers 122 so long as good epitaxialgrowth may be achieved during later processing described below. The HM114 and portions of the self-aligned spacers adjacent the fins 110 inthe pFET active regions 101-1 are removed using RIE and wet etch orother suitable processing.

FIG. 13 shows a cross-sectional view 1300 of the FIG. 12 structurefollowing formation of the top junctions or top source/drain regions 136for the pFET VTFETs. The top source/drain regions 136 may be formedusing processing similar to that described above with respect toformation of the bottom source/drain region 104. The top source/drainregions 136 utilize p-type dopants. The mask 134 is removed usingprocessing similar to that described above with respect to removal ofthe mask 128.

It should be appreciated that while FIGS. 10-13 illustrate a processwherein the nFET top source/drain regions 130 are formed prior to thepFET top source/drain regions 136, embodiments are not so limited. Inother embodiments, this processing may be reversed such that the pFETtop source/drain regions 136 are formed prior to the nFET topsource/drain regions 130.

FIG. 14 shows a cross-sectional view 1400 of the FIG. 13 structurefollowing removal of the encapsulation layer 132 and formation of anitride layer 138 over the nFET top source/drain regions 130 and thepFET top source/drain regions 136. The encapsulation layer 132 may beremoved using wet etch or other suitable processing. The nitride layer138 may be formed by recessing the nFET top source/drain regions 130 andpFET top source/drain regions 136 followed by deposition or in-situnitridization.

FIG. 15 shows a cross-sectional view 1500 of the FIG. 14 structurefollowing formation of a mask 140 to open the n-n shared region, andfollowing removal of the dummy gate 120 in the n-n shared region. Themask 140 may be formed of similar materials and with similar processingas mask 128. The mask 140 is patterned as illustrated to provide anopening between the fins 110 in the nFET active regions 101-1. Portionsof the oxide layer 126 exposed by the mask 140 are then removed usingRIE or other suitable processing. The dummy gate 120 in the n-n sharedregion is then removed using dry or wet etch processing. The cappinglayer 118 is also removed as illustrated, though the dielectric layer116 remains to provide the gate dielectric as discussed above.

FIG. 16 shows a cross-sectional view 1600 of the FIG. 15 structurefollowing formation of a gate conductor 142 for the nFET VTFETs. Themask 140 is removed prior to formation of the nFET gate conductor 142,using processing similar to that described above with respect to removalof the mask 128.

The nFET gate conductor 142 may be formed of a WFM, and thus may also bereferred to herein as nFET WFM 142. The nFET WFM 142 may be titanium(Ti), aluminum (Al), titanium aluminum (TiAl), titanium aluminum carbon(TiAlC), a combination of Ti and Al alloys, a stack which includes abarrier layer (e.g., of TiN or another suitable material) followed byone or more of the aforementioned WFM materials, etc. The nFET gateconductor 142, also referred to as nFET WFM 142, may be formed using aconformal deposition process such as ALD. As illustrated by the bolddashed lines in FIG. 16, formation of the nFET WFM 142 may include ALDdeposition from both sides layer-by-layer, with subsequent layerspinching off the remaining space until the region is completely filledas illustrated. This layer-by-layer deposition of the nFET WFM 142 mayresult in seams as indicated by the bold dashed lines in FIG. 16. Thelayer by layer deposition by ALD could form a metal layer ring due tolateral tunneling deposition as shown in FIG. 16.

FIG. 17 shows a cross-sectional view 1700 of the FIG. 16 structurefollowing an optional step of planarizing the nFET WFM 142. The nFET WFM142 may be planarized using CMP or other suitable processing such thatthe top surface of the nFET WFM 142 is substantially coplanar with thetop surface of the nitride 138.

FIG. 18 shows a cross-sectional view 1800 of the FIG. 17 structurefollowing formation of the gate conductor 144 for the pFET VTFETs in thep-p shared region using processing similar to that described above withrespect to FIGS. 15 and 16. A mask may be formed to open the p-p sharedregion, followed by removal of portions of the oxide layer in the p-pshared region and removal of the dummy gate 120 in the p-p sharedregion. It should be noted that while the capping layer 118 is removedin the n-n shared region, the capping layer 118 is not removed in thep-p shared region. In another embodiment, the capping layer 118 isremoved in the p-p shared region before the pFET gate conductor 144 isformed.

The pFET gate conductor 144 may be formed of a WFM, and thus may also bereferred to herein as pFET WFM 144. The pFET WFM 144 may be formed ofTiN, TaN, or another suitable material. In some embodiments, the pFETWFM 144 includes a metal stack, where a thicker barrier layer (e.g., ofTiN, TaN, etc.) is formed followed by a WFM such as titanium (Ti),aluminum (Al), titanium aluminum (TiAl), titanium aluminum carbon(TiAlC), or any combination of Ti and Al alloys. The difference betweenthe pFET WFM 144 and the nFET WFM 142 may be different thickness of thebarrier layer, use of different WFM materials, different thickness ofWFM materials, combinations thereof, etc. The pFET gate conductor 144,also referred to as pFET WFM 144, may be formed using a conformaldeposition process such as ALD in a manner similar to that describedabove with respect to formation of the nFET WFM 142. As illustrated bythe bold dashed lines in FIG. 18, formation of the pFET WFM 144 mayinclude ALD deposition from both sides layer-by-layer, with subsequentlayers pinching off the remaining space until the region is completelyfilled as illustrated. This layer-by-layer deposition of the pFET WFM144 may result in some discontinuity or interface as indicated by thebold dash-dot lines in FIG. 18.

The cross-sectional view 1800 of FIG. 18 further illustrates gateplanarization (e.g., using CMP or another suitable process) followingformation of the pFET WFM 144. The gate planarization removes thenitride 138, and stops at the top surfaces of the nFET top source/drainregions 130 and pFET top source/drain regions 136. It should beappreciated, however, that in other embodiments the gate planarizationmay not remove the nitride 138 as in some cases the nitride 138 helps inintegration during downstream processing described below. Thus, althoughnot shown in subsequent figures, the nitride layer 138 may remain insome embodiments following the gate planarization.

FIG. 19 shows a cross-sectional view 1900 of the FIG. 18 structurefollowing formation of a mask 146 to open the n-n and p-p sharedregions, and following n-n and p-p isolation gate cuts. The mask 146 maybe formed with similar materials and sizing as that of the mask 128. Theopenings in the mask 146 are aligned to the n-n and p-p shared regions(e.g., between the fins 110 in the active regions 101-1 and 101-2). Anisolation gate cut is then performed using RIE or other suitableprocessing to remove portions of the nFET WFM 142 and pFET WFM 144exposed by the openings in the mask 146 not protected by theself-aligned spacers 122. As illustrated, dielectric layer 118 andbottom spacer 106 exposed by the mask 146 not protected by theself-aligned spacers 122 are also removed.

FIG. 20 shows a cross-sectional view 2000 of the FIG. 19 structurefollowing formation of a self-aligned inner spacer 148. The self-alignedinner spacer 148 is formed over the exposed sidewalls of the nFET WFM142, the pFET WFM 144 and the self-aligned spacers 122. The self-alignedinner spacer 148 may be formed of any suitable material that willisolate the surrounding materials (e.g., nFET WFM 142 and pFET WFM 144)from contact material formed during later processing described below.The self-aligned inner spacer 148 may have a uniform thickness in therange of 5 nm to 15 nm, although other thicknesses above or below thisrange may be used as desired for a particular application.

FIG. 21 shows a cross-sectional view 2100 of the FIG. 20 structurefollowing fill with an oxide 150. The oxide 150 may be formed of thesame material as oxide 126, and thus is denoted in FIG. 21 andsubsequent figures as 126/150.

FIG. 22 shows a cross-sectional view 2200 of the FIG. 21 structurefollowing patterning of a mask 152 to open the n-p shared gate region.The mask 152 may be formed of similar materials and with similarprocessing as that of mask 128.

FIG. 23 shows a cross-sectional view 2300 of the FIG. 22 structurefollowing formation of openings for contacts to the top source/drainregions 130 and 136, and to the bottom source/drain region 106 in then-n and p-p shared regions. These openings may be formed by patterning amask using processing similar to that described with respect to mask152.

FIG. 24 shows a cross-sectional view 2400 of the FIG. 23 structurefollowing formation of contact material 154. The contact material 154may be formed using any suitable deposition process such as PVD,chemical vapor deposition (CVD), ALD, etc. The contact material 154 maycomprise titanium/titanium nitride (Ti/TiN) plus tungsten (W) or anothersuitable material such as Ti/TiN plus cobalt (Co), etc. As shown in FIG.24, the contact material 154 is formed to overfill the structure.

FIG. 25 shows a cross-sectional view 2500 of the FIG. 24 structurefollowing planarization using CMP or another suitable process toseparate the contact material 154 into separate contacts 154-1 through154-9.

The contacts 154-1 and 154-3 connect to the nFET top source/drainregions 130, and the contacts 154-5 and 154-7 contact the pFET topsource/drain regions 136.

The contacts 154-2 and 154-6 provide bottom source/drain self-alignedcontacts between the n-n and p-p regions, respectively. The contacts154-2 and 154-6 further abut the etched RMG gate edges in the n-n andp-p regions. The contacts 154-2 and 154-6 connect to the bottomsource/drain region 106 in the n-n and p-p shared regions, respectively.

The contact 154-4 provides an nFET gate to pFET gate self-aligned strapto electrically connect adjacent opposite type gates. The contact 154-4connects to the nFET WFM 142 and pFET WFM 144 in the n-p shared gateregion.

The contacts 154-8 and 154-9 provide gate contacts for the nFET and pFETdevices at the edges of the row as illustrated.

In some embodiments, a semiconductor structure comprises a substrate, abottom source/drain region disposed on a top surface of the substrate,and a plurality of fins disposed over a top surface of the bottomsource/drain region. The fins provide vertical transport channels forone or more VTFETs. The semiconductor structure also comprises at leastone self-aligned shared contact disposed between an adjacent pair of theplurality of fins. The adjacent pair of the plurality of fins comprisesa first fin providing a first vertical transport channel for a firstVTFET and a second fin providing a second vertical transport channel fora second VTFET.

The first VTFET and the second VTFET may comprise one of n-type andp-type VTFETs, and the at least one self-aligned shared contact maycomprise a contact to a portion of the bottom source/drain region sharedby the first VTFET and the second VTFET.

The first VTFET may comprise an n-type VTFET and the second VTFET maycomprise a p-type VTFET, and the at least one self-aligned sharedcontact may comprise a gate contact to a first gate conductorsurrounding the first fin of the first VTFET and a second gate conductorsurrounding the second fin of the second VTFET. The first gate conductormay comprise a first replacement metal gate WFM material, and the secondgate conductor comprises a second replacement metal gate WFM materialdifferent than the first replacement metal gate WFM material.

The semiconductor structure may further comprise a bottom spacerdisposed over the bottom source/drain region surrounding a portion ofsidewalls of the plurality of fins, a gate dielectric disposed over thebottom spacer and surrounding a portion of the sidewalls of theplurality of fins, top source/drain regions disposed over top surfacesof the plurality of fins, a first gate conductor disposed over the gatedielectric surrounding ones of the plurality of fins providing verticaltransport channels for n-type VTFETs, a second gate conductor disposedover the gate dielectric surrounding ones of the plurality of finsproviding vertical transport channels for p-type VTFETs, andself-aligned spacers disposed over the gate dielectric, the first gateconductor and the second gate conductor surrounding a portion of thesidewalls of the plurality of fins and sidewalls of the top source/drainregions.

The plurality of fins may comprise at least a first pair of adjacentfins providing respective vertical transport channels for a first pairof VTFETs, the first pair of VTFETs comprising one of n-type VTFETs andp-type VTFETs. The semiconductor structure may further comprise innerspacers disposed on sidewalls of the gate dielectric, one of the firstgate conductor and the second gate conductor, and the self-alignedspacers between the first pair of adjacent fins, and a first contact tothe bottom source/drain region disposed between the inner spacersdisposed between the first pair of adjacent fins, the first contactbeing shared by the first pair of VTFETs.

The plurality of fins may further comprise at least a second pair ofadjacent fins providing respective vertical transport channels for asecond pair of VTFETs, the second pair of VTFETs comprising the otherone of n-type VTFETs and p-type VTFETs. The semiconductor structure mayfurther comprise inner spacers disposed on sidewalls of the gatedielectric, the other one of the first gate conductor and the secondgate conductor, and the self-aligned spacers disposed between the secondpair of adjacent fins, and a second contact to the bottom source/drainregion disposed between the inner spacers disposed between the secondpair of adjacent fins, the second contact being shared by the secondpair of VTFETs.

The first contact to the bottom source/drain region may be self-alignedto etched edges of said one of the first gate conductor and the secondgate conductor disposed between the first pair of adjacent fins, and thesecond contact to the bottom source/drain region may be self-aligned toetched edges of said other one of the first gate conductor and thesecond gate conductor disposed between the second pair of adjacent fins.

The plurality of fins may further comprise at least a third pair ofadjacent fins, the third pair of adjacent fins comprising one of thefins from the first pair of adjacent fins and one of the fins from thesecond pair of adjacent fins, and the semiconductor structure mayfurther comprise a self-aligned shared gate contact disposed over thebottom spacer between the first gate conductor and the second gateconductor. The self-aligned shared gate contact provides a strappingthat electrically connects the first gate conductor and the second gateconductor.

In some embodiments, integrated circuits comprise one or more VTFETs orother semiconductor structures described above.

In some embodiments, a method of forming a semiconductor structurecomprises forming a bottom source/drain region over a top surface of asubstrate, forming a plurality of fins over a top surface of the bottomsource/drain region, the fins providing vertical transport channels forone or more VTFETs, and forming at least one self-aligned shared contactbetween an adjacent pair of the plurality of fins, the adjacent pair ofthe plurality of fins comprising a first fin providing a first verticaltransport channel for a first VTFET and a second fin providing a secondvertical transport channel for a second VTFET.

The first VTFET and the second VTFET may comprise one of n-type andp-type VTFETs, and the at least one self-aligned shared contact maycomprise a contact to a portion of the bottom source/drain region sharedby the first VTFET and the second VTFET.

The first VTFET may comprise an n-type VTFET and the second VTFET maycomprise a p-type VTFET, and the at least one self-aligned sharedcontact comprises a gate contact to a first gate conductor surroundingthe first fin of the first VTFET and a second gate conductor surroundingthe second fin of the second VTFET.

The method may further comprise forming a bottom spacer over the bottomsource/drain region surrounding a portion of sidewalls of the pluralityof fins, forming an interlayer on exposed sidewalls of the plurality offins, forming an oxide over top surfaces of the plurality of fins,forming a hard mask over top surfaces of the oxide, forming a gatedielectric over the top surface of the bottom spacer, the interlayer,sidewalls of the oxide and the hard mask, and forming a capping layerover the gate dielectric.

The method may further comprise depositing a dummy gate over the cappinglayer, planarizing the dummy gate such that a top surface of the dummygate is substantially coplanar with the capping layer over the topsurface of the hard mask, recessing the dummy gate below a bottomsurface of the oxide, recessing the capping layer and the gatedielectric to be substantially coplanar with the recessed dummy gate,and forming self-aligned spacers over the recessed dummy gate andsurrounding exposed sidewalls of the plurality of fins, the oxide andthe hard mask.

The method may further comprise forming first masks over the recesseddummy gate between n-n shared regions for adjacent pairs of theplurality of fins providing vertical transport channels for n-typeVTFETs and between p-p shared regions for adjacent pairs of theplurality of fins providing vertical transport channels for p-typeVTFETs, and removing the recessed dummy gate exposed by the self-alignedspacers at ends of the plurality of fins, in the n-n shared regions, andin the p-p shared regions.

The method may further comprise filling an oxide, planarizing the oxideto be substantially coplanar with a top surface of the hard mask,patterning a second mask over the oxide to expose top surfaces ofadjacent pairs of the plurality of fins in one of the n-n and p-p sharedregions, removing portions of the hard mask exposed by the second maskto reveal top surfaces of the adjacent pairs of the plurality of fins inone of the n-n and p-p shared regions, forming top source/drain regionsover the revealed top surfaces of the adjacent pairs of the plurality offins in said one of the n-n and p-p shared regions, removing the secondmask, forming an encapsulation layer, patterning a third mask over theencapsulation layer to expose top surfaces of adjacent pairs of theplurality of fins in said other one of the n-n and p-p shared regions,removing portions of the hard mask exposed by the third mask to revealtop surfaces of the adjacent pairs of the plurality of fins in saidother one of the n-n and p-p shared regions, forming top source/drainregions over the revealed top surfaces of the adjacent pairs of theplurality of fins in said other one of the n-n and p-p shared regions,and removing the third mask and the encapsulation layer.

The method may further comprise recessing the top/source drain regions,forming nitride layers over top surfaces of the recessed topsource/drain regions, patterning a fourth mask to expose theself-aligned spacers and recessed dummy gate formed between adjacentpairs of the plurality of fins in said one of the n-n and p-p sharedregions, removing the oxide over the recessed dummy gate surrounding theadjacent pairs of the plurality of fins in said one of the n-n and p-pshared regions, removing the recessed dummy gate surrounding theadjacent pairs of the plurality of fins in said one of the n-n and p-pshared regions, removing the fourth mask, forming a first gate conductorsurrounding the adjacent pairs of the plurality of fins in said one ofthe n-n and p-p shared regions, patterning a fifth mask to expose theself-aligned spacers and recessed dummy gate formed between adjacentpairs of the plurality of fins in said other one of the n-n and p-pshared regions, removing the oxide over the recessed dummy gatesurrounding the adjacent pairs of the plurality of fins in said otherone of the n-n and p-p shared regions, removing the recessed dummy gatesurrounding the adjacent pairs of the plurality of fins in said otherone of the n-n and p-p shared regions, removing the fifth mask, andforming a second gate conductor surrounding the adjacent pairs of theplurality of fins in said other one of the n-n and p-p shared regions.

The method may further comprise planarizing the first and second gateconductors to expose top surfaces of the top source/drain regions,patterning a sixth mask to expose the first gate conductor and thesecond gate conductor in the n-n and p-p shared regions, removingportions of the first gate conductor, the second gate conductor and thebottom spacer exposed by the patterned sixth mask to isolate gateregions for each of the plurality of fins, and forming inner spacers onsidewalls of the first gate conductor, the second gate conductor, andthe self-aligned spacers.

The method may further comprise filling an oxide, patterning a seventhmask to expose the first gate conductor and the second gate conductorbetween adjacent pairs of the plurality of fins in the n-p sharedregions, removing portions of the first gate conductor and the secondgate conductor exposed by the patterned seventh mask, removing theseventh mask, patterning an eighth mask to expose top surfaces of thetop source/drain regions and regions between the self-aligned spacersbetween adjacent pairs of the plurality of fins, and removing portionsof the oxide exposed by the patterned eighth mask to expose: topsurfaces of the top source/drain regions; portions of the bottom spacerbetween adjacent pairs of the plurality of fins in the n-p shareregions; and portions of the bottom source/drain region between adjacentpairs of the plurality of fins in the n-n and p-p shared regions.

The method may further comprise forming top source/drain contacts,forming shared bottom source/drain contacts to the bottom source/drainregion between adjacent pairs of the plurality of fins in the n-n andp-p shared regions, and forming shared gate contacts to the first gateconductor and the second gate conductor between adjacent pairs of theplurality of fins in the n-p shared regions.

It is to be appreciated that the various materials, processing methods(e.g., etch types, deposition types, etc.) and dimensions provided inthe discussion above are presented by way of example only. Various othersuitable materials, processing methods, and dimensions may be used asdesired.

Semiconductor devices and methods for forming same in accordance withthe above-described techniques can be employed in various applications,hardware, and/or electronic systems. Suitable hardware and systems forimplementing embodiments of the invention may include, but are notlimited to, sensors an sensing devices, personal computers,communication networks, electronic commerce systems, portablecommunications devices (e.g., cell and smart phones), solid-state mediastorage devices, functional circuitry, etc. Systems and hardwareincorporating the semiconductor devices are contemplated embodiments ofthe invention. Given the teachings provided herein, one of ordinaryskill in the art will be able to contemplate other implementations andapplications of embodiments of the invention.

Various structures described above may be implemented in integratedcircuits. The resulting integrated circuit chips can be distributed bythe fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A semiconductor structure, comprising: asubstrate; a bottom source/drain region disposed on a top surface of thesubstrate; a plurality of fins disposed over a top surface of the bottomsource/drain region, the fins providing vertical transport channels forone or more vertical transport field-effect transistors; and at leastone self-aligned shared contact disposed between an adjacent pair of theplurality of fins, the adjacent pair of the plurality of fins comprisinga first fin providing a first vertical transport channel for a firstvertical transport field-effect transistor and a second fin providing asecond vertical transport channel for a second vertical transportfield-effect transistor.
 2. The semiconductor structure of claim 1,wherein the first vertical transport field-effect transistor and thesecond vertical transport field-effect transistor comprise one of n-typeand p-type vertical transport field-effect transistors, and wherein theat least one self-aligned shared contact comprises a contact to aportion of the bottom source/drain region shared by the first verticaltransport field-effect transistor and the second vertical transportfield-effect transistor.
 3. The semiconductor structure of claim 1,wherein the first vertical transport field-effect transistor comprisesan n-type vertical transport field-effect transistor and the secondvertical transport field-effect transistor comprises a p-type verticaltransport field-effect transistor, and wherein the at least oneself-aligned shared contact comprises a gate contact to a first gateconductor surrounding the first fin of the first vertical transportfield-effect transistor and a second gate conductor surrounding thesecond fin of the second vertical transport field-effect transistor. 4.The semiconductor structure of claim 3, wherein the first gate conductorcomprises a first replacement metal gate work function metal material,and wherein the second gate conductor comprises a second replacementmetal gate work function metal material different than the firstreplacement metal gate work function metal material.
 5. Thesemiconductor structure of claim 1, further comprising: a bottom spacerdisposed over the bottom source/drain region surrounding a portion ofsidewalls of the plurality of fins; a gate dielectric disposed over thebottom spacer and surrounding a portion of the sidewalls of theplurality of fins; top source/drain regions disposed over top surfacesof the plurality of fins; a first gate conductor disposed over the gatedielectric surrounding ones of the plurality of fins providing verticaltransport channels for n-type vertical transport field-effecttransistors; a second gate conductor disposed over the gate dielectricsurrounding ones of the plurality of fins providing vertical transportchannels for p-type vertical transport field-effect transistors; andself-aligned spacers disposed over the gate dielectric, the first gateconductor and the second gate conductor surrounding a portion of thesidewalls of the plurality of fins and sidewalls of the top source/drainregions.
 6. The semiconductor structure of claim 5, wherein theplurality of fins comprise at least a first pair of adjacent finsproviding respective vertical transport channels for a first pair ofvertical transport field-effect transistors, the first pair of verticaltransport field-effect transistors comprising one of n-type verticaltransport field-effect transistors and p-type vertical transportfield-effect transistors, and further comprising: inner spacers disposedon sidewalls of the gate dielectric, one of the first gate conductor andthe second gate conductor, and the self-aligned spacers between thefirst pair of adjacent fins; and a first contact to the bottomsource/drain region disposed between the inner spacers disposed betweenthe first pair of adjacent fins, the first contact being shared by thefirst pair of vertical transport field-effect transistors.
 7. Thesemiconductor structure of claim 6, wherein the plurality of finsfurther comprise at least a second pair of adjacent fins providingrespective vertical transport channels for a second pair of verticaltransport field-effect transistors, the second pair of verticaltransport field-effect transistors comprising the other one of n-typevertical transport field-effect transistors and p-type verticaltransport field-effect transistors, and further comprising: innerspacers disposed on sidewalls of the gate dielectric, the other one ofthe first gate conductor and the second gate conductor, and theself-aligned spacers disposed between the second pair of adjacent fins;and a second contact to the bottom source/drain region disposed betweenthe inner spacers disposed between the second pair of adjacent fins, thesecond contact being shared by the second pair of vertical transportfield-effect transistors.
 8. The semiconductor structure of claim 7,wherein the first contact to the bottom source/drain region isself-aligned to etched edges of said one of the first gate conductor andthe second gate conductor disposed between the first pair of adjacentfins, and wherein the second contact to the bottom source/drain regionis self-aligned to etched edges of said other one of the first gateconductor and the second gate conductor disposed between the second pairof adjacent fins.
 9. The semiconductor structure of claim 7, wherein theplurality of fins further comprises at least a third pair of adjacentfins, the third pair of adjacent fins comprising one of the fins fromthe first pair of adjacent fins and one of the fins from the second pairof adjacent fins, and further comprising a self-aligned shared gatecontact disposed over the bottom spacer between the first gate conductorand the second gate conductor.
 10. The semiconductor structure of claim9, wherein the self-aligned shared gate contact provides a strappingthat electrically connects the first gate conductor and the second gateconductor.
 11. An integrated circuit comprising: one or more verticaltransport field-effect transistors comprising: a substrate; a bottomsource/drain region disposed on a top surface of the substrate; aplurality of fins disposed over a top surface of the bottom source/drainregion, the fins providing vertical transport channels for the one ormore vertical transport field-effect transistors; and at least oneself-aligned shared contact disposed between an adjacent pair of theplurality of fins, the adjacent pair of the plurality of fins comprisinga first fin providing a first vertical transport channel for a firstvertical transport field-effect transistor and a second fin providing asecond vertical transport channel for a second vertical transportfield-effect transistor.
 12. The integrated circuit of claim 11, whereinthe first vertical transport field-effect transistor and the secondvertical transport field-effect transistor comprise one of n-type andp-type vertical transport field-effect transistors, and wherein the atleast one self-aligned shared contact comprises a contact to a portionof the bottom source/drain region shared by the first vertical transportfield-effect transistor and the second vertical transport field-effecttransistor.
 13. The integrated circuit of claim 11, wherein the firstvertical transport field-effect transistor comprises an n-type verticaltransport field-effect transistor and the second vertical transportfield-effect transistor comprises a p-type vertical transportfield-effect transistor, and wherein the at least one self-alignedshared contact comprises a gate contact to a first gate conductorsurrounding the first fin of the first vertical transport field-effecttransistor and a second gate conductor surrounding the second fin of thesecond vertical transport field-effect transistor.
 14. The integratedcircuit of claim 13, wherein the first gate conductor comprises a firstreplacement metal gate work function metal material, and wherein thesecond gate conductor comprises a second replacement metal gate workfunction metal material different than the first replacement metal gatework function metal material.
 15. A method of forming a semiconductorstructure, comprising: forming a bottom source/drain region over a topsurface of a substrate; forming a plurality of fins over a top surfaceof the bottom source/drain region, the fins providing vertical transportchannels for one or more vertical transport field-effect transistors;and forming at least one self-aligned shared contact between an adjacentpair of the plurality of fins, the adjacent pair of the plurality offins comprising a first fin providing a first vertical transport channelfor a first vertical transport field-effect transistor and a second finproviding a second vertical transport channel for a second verticaltransport field-effect transistor.
 16. The method of claim 15, whereinthe first vertical transport field-effect transistor and the secondvertical transport field-effect transistor comprise one of n-type andp-type vertical transport field-effect transistors, and wherein the atleast one self-aligned shared contact comprises a contact to a portionof the bottom source/drain region shared by the first vertical transportfield-effect transistor and the second vertical transport field-effecttransistor.
 17. The method of claim 15, wherein the first verticaltransport field-effect transistor comprises an n-type vertical transportfield-effect transistor and the second vertical transport field-effecttransistor comprises a p-type vertical transport field-effecttransistor, and wherein the at least one self-aligned shared contactcomprises a gate contact to a first gate conductor surrounding the firstfin of the first vertical transport field-effect transistor and a secondgate conductor surrounding the second fin of the second verticaltransport field-effect transistor.
 18. The method of claim 15, furthercomprising: forming a bottom spacer over the bottom source/drain regionsurrounding a portion of sidewalls of the plurality of fins; forming aninterlayer on exposed sidewalls of the plurality of fins; forming anoxide over top surfaces of the plurality of fins; forming a hard maskover top surfaces of the oxide; forming a gate dielectric over the topsurface of the bottom spacer, the interlayer, sidewalls of the oxide andthe hard mask; and forming a capping layer over the gate dielectric. 19.The method of claim 18, further comprising: depositing a dummy gate overthe capping layer; planarizing the dummy gate such that a top surface ofthe dummy gate is substantially coplanar with the capping layer over thetop surface of the hard mask; recessing the dummy gate below a bottomsurface of the oxide; recessing the capping layer and the gatedielectric to be substantially coplanar with the recessed dummy gate;and forming self-aligned spacers over the recessed dummy gate andsurrounding exposed sidewalls of the plurality of fins, the oxide andthe hard mask.
 20. The method of claim 19, further comprising: formingfirst masks over the recessed dummy gate between n-n shared regions foradjacent pairs of the plurality of fins providing vertical transportchannels for n-type vertical transport field-effect transistors andbetween p-p shared regions for adjacent pairs of the plurality of finsproviding vertical transport channels for p-type vertical transportfield-effect transistors; and removing the recessed dummy gate exposedby the self-aligned spacers at ends of the plurality of fins, in the n-nshared regions, and in the p-p shared regions.
 21. The method of claim20, further comprising: filling an oxide; planarizing the oxide to besubstantially coplanar with a top surface of the hard mask; patterning asecond mask over the oxide to expose top surfaces of adjacent pairs ofthe plurality of fins in one of the n-n and p-p shared regions; removingportions of the hard mask exposed by the second mask to reveal topsurfaces of the adjacent pairs of the plurality of fins in one of then-n and p-p shared regions; forming top source/drain regions over therevealed top surfaces of the adjacent pairs of the plurality of fins insaid one of the n-n and p-p shared regions; removing the second mask;forming an encapsulation layer; patterning a third mask over theencapsulation layer to expose top surfaces of adjacent pairs of theplurality of fins in said other one of the n-n and p-p shared regions;removing portions of the hard mask exposed by the third mask to revealtop surfaces of the adjacent pairs of the plurality of fins in saidother one of the n-n and p-p shared regions; forming top source/drainregions over the revealed top surfaces of the adjacent pairs of theplurality of fins in said other one of the n-n and p-p shared regions;and removing the third mask and the encapsulation layer.
 22. The methodof claim 21, further comprising: recessing the top/source drain regions;forming nitride layers over top surfaces of the recessed topsource/drain regions; patterning a fourth mask to expose theself-aligned spacers and recessed dummy gate formed between adjacentpairs of the plurality of fins in said one of the n-n and p-p sharedregions; removing the oxide over the recessed dummy gate surrounding theadjacent pairs of the plurality of fins in said one of the n-n and p-pshared regions; removing the recessed dummy gate surrounding theadjacent pairs of the plurality of fins in said one of the n-n and p-pshared regions; removing the fourth mask; forming a first gate conductorsurrounding the adjacent pairs of the plurality of fins in said one ofthe n-n and p-p shared regions; patterning a fifth mask to expose theself-aligned spacers and recessed dummy gate formed between adjacentpairs of the plurality of fins in said other one of the n-n and p-pshared regions; removing the oxide over the recessed dummy gatesurrounding the adjacent pairs of the plurality of fins in said otherone of the n-n and p-p shared regions; removing the recessed dummy gatesurrounding the adjacent pairs of the plurality of fins in said otherone of the n-n and p-p shared regions; removing the fifth mask; andforming a second gate conductor surrounding the adjacent pairs of theplurality of fins in said other one of the n-n and p-p shared regions.23. The method of claim 22, further comprising: planarizing the firstand second gate conductors to expose top surfaces of the topsource/drain regions; patterning a sixth mask to expose the first gateconductor and the second gate conductor in the n-n and p-p sharedregions; removing portions of the first gate conductor, the second gateconductor and the bottom spacer exposed by the patterned sixth mask toisolate gate regions for each of the plurality of fins; and forminginner spacers on sidewalls of the first gate conductor, the second gateconductor, and the self-aligned spacers.
 24. The method of claim 23,further comprising: filling an oxide; patterning a seventh mask toexpose the first gate conductor and the second gate conductor betweenadjacent pairs of the plurality of fins in the n-p shared regions;removing portions of the first gate conductor and the second gateconductor exposed by the patterned seventh mask; removing the seventhmask; patterning an eighth mask to expose top surfaces of the topsource/drain regions and regions between the self-aligned spacersbetween adjacent pairs of the plurality of fins; and removing portionsof the oxide exposed by the patterned eighth mask to expose: topsurfaces of the top source/drain regions; portions of the bottom spacerbetween adjacent pairs of the plurality of fins in the n-p shareregions; and portions of the bottom source/drain region between adjacentpairs of the plurality of fins in the n-n and p-p shared regions. 25.The method of claim 24, further comprising: forming top source/draincontacts; forming shared bottom source/drain contacts to the bottomsource/drain region between adjacent pairs of the plurality of fins inthe n-n and p-p shared regions; and forming shared gate contacts to thefirst gate conductor and the second gate conductor between adjacentpairs of the plurality of fins in the n-p shared regions.